Risk factors for fatal lateral condylar fracture of the third metacarpus/metatarsus in UK racing

REASONS FOR PERFORMING STUDY: Lateral condylar fractures of the third metacarpus/metatarsus are the most common cause of equine fatality on UK racecourses. Identification of risk factors for such injuries and the subsequent implementation of intervention strategies could significantly reduce the total number of racecourse fatalities. OBJECTIVES: To identify horse-, race- and course-level risk factors for fatal lateral condylar fracture in Thoroughbreds on UK racecourses. METHODS: Case-control study designs were used. Case horses were defined as those that were subjected to euthanasia having sustained an irreparable lateral condylar fracture while racing at any of the 59 UK racecourses. Case races were defined as those in which one or more horses sustained a fatal lateral condylar fracture. Three controls for each case horse were selected at random from the race in which the case was running. Three controls for each case race were selected at random from all races of the same type held in the same year. Ninety-eight cases were included in the study. Conditional logistic regression was used to identify the relationship between a number of independent variables and the likelihood of fracture. RESULTS: Horses doing no gallop work during training and those in their first year of racing were at significantly increased risk of fracture on the racecourse. Case horses were also more likely to have started racing as 3- or 4-year-olds. Fractures were found to be more likely in longer races with a larger number of runners, races in which professional jockeys were not permitted to ride and races in which the going was described as firm or hard. CONCLUSIONS AND POTENTIAL RELEVANCE: Modifications to training schedules, specifically within the first year of racing, may have a large impact on the risk of fatal lateral condylar fracture on the racecourse. Horses should do some gallop work in training and our results suggest that the minimum distance galloped should be between 201 m (1 furlong) and 1609 m (8 furlongs) per week. The association with age at first race requires further investigation for flat and National Hunt racing separately. A reduction in the number of races taking place on very firm going could have an impact on the number of lateral condylar fractures.     

A comparative study on the prevalence of Theileria equi and Babesia caballi infections in horse sub-populations in Turkey

Blood and serum samples were taken from 481 horses, from a stud farm or a racecourse, and tested by microscopic examination of blood smears and cELISA for Theileria equi (T. equi) and Babesia caballi (B. caballi) infections. At the time of sampling, animals were also examined for tick infestations and clinical disease, which were not observed in any of the sampled horses. During the microscopic examination of thin blood smears, parasites were detected in the three horses from the racecourse. Overall seroprevalence of infection was detected as 18.50% (89 of 481 horses) by cELISA, with T. equi being significantly more prevalent than B. caballi. Of the 481 blood samples, 78 (16.21%) were serologically positive for T. equi and 4 (0.83%) were serologically positive for B. caballi. In addition, 7 (1.46%) samples were positive for both T. equi and B. caballi antibodies. Seropositivity rates in the racecourse horses were higher than those determined in the stud farm horses. The rates for T. equi, B. caballi and both species were 13.39, 0.52 and 0% in the horses from the stud farm and 27, 2 and 7% in the racecourse horses, respectively. These results indicate that equine piroplasmosis is more common in racehorses than studhorses and therefore it might be a serious concern in horses that participate to international races.     

Racecourse fracture management. Part 1: Incidence and principles

Equine fractures occurring during racing are an emotive subject. Attending veterinary surgeons have an obligation to be well informed and decisive; actions taken and advice given are frequently subject to public scrutiny and there are in addition important welfare, financial and litigious considerations. This paper is the first of a trilogy of reviews aimed at providing veterinary surgeons with up to date information on racecourse fracture management. It details incidence and predisposing factors, contemporary reviews on pathogenesis and discusses insurance implications. It also gives guidelines for acute evaluation and first aid management including sedation and analgesia. The second paper will describe techniques for temporary immobilisation and transport and the third will report up to date recommendations and emergency care of specific fractures.     

Descriptive epidemiology of fracture,tendon and suspensory ligament injuries in National Hunt racehorses in training

Reasons for performing study: While fractures and tendon injuries are known to be important diseases in National Hunt (NH) racehorses during racing, there are no accurate estimates of their incidence in NH training yards. Objectives: To estimate the incidence of fractures and tendon and suspensory ligament injuries (TLIs) in NH racehorses in training; to describe the injuries incurred and to compare injury incidence rates by horse age, trainer, gender and background (ex‐flat vs. ex‐store horses). Methods: Cohort data were collected from 14 UK NH training yards for 2 racing seasons. Daily exercise regimens and details of fractures and TLIs occurring in study horses were recorded. Results: Data were gathered from 1223 horses that spent 9466 months at risk of injury. The fracture incidence rate was 1.1/100 horse months and varied significantly by trainer (P<0.001) but not by gender, age or background. The pelvis and third metacarpal bone (MCIII) were the most common fracture sites, although this varied between racing and training. The TLI incidence rate was 1.9/100 horse months and varied significantly by trainer (P = 0.05) and age (P<0.001) but not by gender or background. However, exstore horses were significantly more likely to have a TLI on the racecourse than ex‐flat horses (P = 0.01). Superficial digital flexor injuries accounted for 89% of all TLIs, the remainder being suspensory ligament injuries. Conclusions and potential relevance: Fractures and TLIs are important causes of morbidity and mortality in NH racehorses in training in England. This study provides accurate estimates of their incidence in this population and provides a baseline against which to monitor the effect of future interventions.     

Horse-level risk factors for fatal distal limb fracture in racing Thoroughbreds in the UK

REASONS FOR PERFORMING STUDY: Fractures below the level of the radius or tibia (distal limb fractures) are the most common cause of equine fatality on UK racecourses; however, little is known about their epidemiology or aetiology. Identification of risk factors could enable intervention strategies to be designed to reduce the number of fatalities. OBJECTIVES: To identify horse-level risk factors for fatal distal limb fracture in Thoroughbreds on UK racecourses. METHODS: A case-control study design was used. Fractures in case horses were confirmed by post mortem examination and 3 matched uninjured controls were selected from the race in which the case horse was running. One hundred and nine cases were included and information was collected about previous racing history, horse characteristics and training schedules. Conditional logistic regression was used to identify the relationship between a number of independent variables and the likelihood of fracture. RESULTS: Horses doing no gallop work during training and those in their first year of racing were at significantly increased risk of fracture on the racecourse. Case horses were also more likely to have trained on a sand gallop, i.e. a gallop described by trainers as being primarily composed of sand. CONCLUSIONS: Modifications to training schedules, specifically within the first year of racing, may have a large impact on the risk of fatal distal limb fracture on the racecourse. Horses should do some gallop work in training and our results suggest that the minimum distance galloped should be between 805-2012 m (4-10 furlongs)/week. POTENTIAL RELEVANCE: The information from this study can be used to alter training schedules in an attempt to reduce the incidence of fatal distal limb fracture in Thoroughbred racehorses. Training should include some gallop work, and further studies, recording the exact level of work, will help to identify an optimum range of training speeds and distances which will reduce the liklihood of catastrophic fracture on the racecourse.     

Catastrophic biaxial proximal sesamoid bone fractures in UK Thoroughbred races (1999–2004): Horse characteristics and racing history

Reason for performing study: Catastrophic biaxial proximal sesamoid bone fractures (PSBF) have not yet been described in detail in the UK racing population. Objectives: To determine the incidence and relative risk (RR) of PSBF in different types of racing in the UK; and to describe horse‐level characteristics and racing histories of horses sustaining these injuries. Methods: Distal limbs were collected from all racehorses suffering catastrophic fractures during racing at all 59 racecourses in the UK, in a prospective study from February 1999 to December 2004. Post mortem investigation identified the anatomical location and type of fracture. Horse, racing history, race and racecourse details were obtained. Characteristics of the horses that sustained PSBF were described. The incidence and RR of PSBF in the different types of racing in the UK were calculated. Results: Thirty‐one horses suffered PSBF during the study period. The incidence of PSBF in all types of race was 0.63 per 10,000 starts (31/494,744). The incidence was highest in flat races on all weather surfaces (1.63 per 10,000 starts: 12/73,467; RR = 4.4 when compared to turf flat racing). Affected horses had an average age of 5.6 years and had started a mean of 28 races at the time of fracture. Conclusion and potential relevance: There is a strong association between type of racing surface and PSBF. Horses competing in flat races on all weather surfaces have an increased risk of PSBF. These fractures appear to happen in experienced horses with several starts, with few fractures occurring within the first season of racing. Further research should focus on identification of underlying pathology of these fractures. Epidemiological studies aimed at the identification of risk factors for PSBF in the UK racing population would require a large number of cases acquired over many years given the relatively low incidence of PSBF.     

Improving the predictability of performance by prerace detection of dorsal metacarpal disease in thoroughbred racehorses

OBJECTIVE: To determine the prevalence of dorsal metacarpal disease in 2-year-old Thoroughbred horses by prerace inspection and to evaluate the effectiveness of a dorsal metacarpal disease detection program on the predictability of race performance (finishing in the order predicted by punters) and the distance between the first- and last-placed horse in a field. DESIGN: A retrospective study using client-owned horses. METHODS: A program of prerace detection of dorsal metacarpal disease using digital palpation of the dorsal aspect of the third metacarpal bone of both forelimbs of 2-year-old Thoroughbreds racing at Ascot racecourse was instituted by the Western Australian Turf Club in December 1995. Horses that had significant pain reaction to digital palpation were considered to have pain due to dorsal metacarpal disease, withdrawn from that day's race and not permitted to race for 6 weeks. The race records of all 2-year-old Thoroughbreds racing at Ascot racecourse from December 1993 until December 1995 were compared with the race results from December 1995 until March 1997, after initiation of the dorsal metacarpal disease detection program. RESULTS: After initiation of the program, horses were racing more predictably over 1100 m (P = 2.09) and 1200 m (P = 3.48). These horses finished closer to the winner over 1100 m (P = 3.39) and over 1200 m (P = 3.13). In 1000 m races, the trend for horses to race more predictably (P = 1.07) and for there to be less distance between first and last (P = 1.72) was not statistically significant. CONCLUSIONS: The program of prerace digital palpation for dorsal metacarpal disease was considered to be beneficial in 2-year-old Thoroughbreds racing over 1100 m and 1200 m, in that they raced more predictably.     

Racing prognosis of horses following surgically repaired olecranon fractures

Olecranon fracture is a common orthopedic problem in juvenile horses. Prognosis for complete fracture healing when various methods of internal fixation are used is good; however, the impact of olecranon fracture stabilization on the likelihood that foals will start on a racecourse is unknown. Medical records of foals undergoing internal fixation for an olecranon fracture were reviewed. The dam's foaling records were obtained and lifetime racing records were then retrieved for both the affected foals and 1 of their siblings. Twenty-two of 24 repaired fractures healed completely, subsequently, 16 of the foals started in at least 1 race. Statistical calculations suggest that when compared with their siblings, the occurrence of olecranon factures requiring internal fixation in juvenile racehorses will not significantly reduce the likelihood that they will race; however, the siblings had significantly more lifetime race starts and higher career earnings.     

Treatment of radial fractures in adult horses: an analysis of 15 clinical cases

Fifteen cases of radial fractures in adult horses weighing more than 300 kg are discussed. Four of the horses were destroyed on humane grounds immediately because of a poor prognosis and expense of internal fixation; and two horses at five days and five weeks, respectively after treatment by cast application was initiated. Internal fixation was used in nine horses but of these only two horses recovered completely and resumed their former activities. In eight cases, two plates were applied, one lateral or medial and the other cranial. The internal fixation techniques of all nine horses were scrutinised and suggestions made for the future treatment of radial fractures. These suggestions are (1) the use of ASIF 5.5 mm cortical bone screws using the total width or thickness of the bone in each case. (2) Application of the dynamic condylar screw with its plate in distal or proximal fractures to allow more support. (3) Incorporation of a cancellous bone graft to the fracture. (4) Possible table recovery to prevent breakdown of the fixation during recovery. It is important that bone plates are applied over the total length of the bone. The fact that only two out of 15 horses survived and recovered completely underlines the problems associated with treatment of radial fractures in the adult horse.     

Race- and course-level risk factors for fatal distal limb fracture in racing Thoroughbreds

REASONS FOR PERFORMING STUDY: Considerable variation in the rates of equine fatality at different racecourses draws attention to probable risk factors at the level of course or race that might be partly responsible. Distal limb fractures are the most common cause of equine fatality on UK racecourses and identification of risk factors for such injuries and subsequent implementation of intervention strategies could significantly reduce the total number of racecourse fatalities. OBJECTIVES: To identify race- and course-level risk factors for fatal distal limb fracture in Thoroughbreds on UK racecourses. METHODS: A case-control study design was used. Case races were defined as those in which one or more horses sustained fatal fracture of the distal limb. Controls were selected in 2 different ways. Firstly, 3 races in which no fracture occurred were selected from all races of the same type held within 5 days of the case race (Analysis 1). Secondly, 3 control races were selected for each case race from all races of the same type held in the same year (Analysis 2). One hundred and nine cases were included in the study. Information about the race and the racecourses was collected from Computer Raceform. Conditional logistic regression was used to identify the relationship between a number of independent variables and the likelihood of fracture in a race. RESULTS: Longer races with a larger number of runners were more likely to contain a fracture. Firmer going and fewer days since the last race on the same course were associated with an increased risk of fracture. The going at the course at the previous race meeting was also associated with the likelihood of fracture. CONCLUSIONS: Modifications to the going on the day of a race and greater emphasis on ground maintenance between race meetings may have an impact on the risk of fatal distal limb fracture during racing. POTENTIAL RELEVANCE: Modification of risk factors such as the going and number of days since the last race meeting could reduce the number of equine fatalities on UK racecourses. The condition of the racecourse may be an important risk factor and future research should focus on the identification of course maintenance techniques that produce the safest possible racing surfaces.     

Dorsal Frontal Fractures of the First Phalanx in the Horse

Dorsal frontal fractures of the first phalanx in nine horses are described. All fractures were in hindlimbs, and two horses were affected bilaterally. Of the eleven fractures, seven were incomplete and nondisplaced, one was complete and nondisplaced, and three were complete and displaced. Two horses with complete displaced fractures had their fractures repaired with lag screw fixation combined with open reduction, and the other seven horses were treated nonsurgically.
All horses were sound on the injured limb within 3 to 6 months of the injury. Lag screw fixation was recommended for horses with complete, displaced dorsal frontal fractures in order to reduce the articular defect and help prevent secondary joint changes. Nonsurgical therapy in the form of stall rest with a heavy support wrap resulted in bony healing of the fracture in 4 to 6 months.
Follow-up was obtained on all nine horses: two were retired for breeding; five performed equal to or better than their previous level of racing performance; one was performing successfully as a combined training horse; and one returned to a lower level of performance due to an unrelated forelimb lameness.     

Fractures of the scapula

Fractures of the scapula are uncommon and the majority of these involve the supraglenoid tubercle in young horses 2 years of age or less. Scapula fractures of the neck or body are rare. Comminuted scapula fractures have been diagnosed in racing breeds (Thoroughbreds and Quarter Horses) and a review of the literature on the different fracture types and their management is presented in this article. The best prognosis for soundness is given for horses treated surgically. The different techniques for surgical management are described here and comments made with reference to nonsurgical management. A residual gait deficit may persist in some horses because of involvement of the suprascapular nerve at the time of injury, during surgery and follow‐up period, the severity of which depends on the degree of nerve trauma.     

Determining the endpoint of an outbreak of equine influenza in a large population of racing Thoroughbreds

Outbreaks of equine influenza (EI) cause major disruption to the racing industry, resulting in cessation of racing until affected horses have recovered from the disease. The introduction of EI to a large population of Thoroughbred horses stabled at a Sydney racecourse provided the opportunity to observe clinical signs and monitor the spread of EI in this predominantly na?ve population and to assist in determining an endpoint to infection spread to allow resumption of racing events.     

Risk factors for Thoroughbred racehorse fatality in jump starts in Victoria, Australia (1989-2004)

REASONS FOR PERFORMING STUDY: The risk of fatality is greater in jump than in flat racing in Victoria, Australia. This is the first study to identify risk factors specific to jump starts in Victoria. OBJECTIVE: To identify risk factors for fatality of Thoroughbred racehorses in jump starts on all racecourses in Victoria, Australia between 1989 and 2004. METHODS: Fatalities comprised all horses that died during or immediately after a jump (hurdle or steeplechase) race or official jump trial and all horses that were subjected to euthanasia within 24 h of an event in which an injury was sustained. The retrospective study involved 191 case starts and 2324 control starts. Univariable and multivariable backward stepwise logistic regression was used to identify risk factors for fatality at any one start. A multiple level model was used with racecourse included as a random effect. RESULTS: In the final multivariable model, the duration of the racing career of the horse, the number of flat, hurdle and steeple starts accumulated in the 60 days prior to the case or control start, the number of flat and jump starts accumulated over the racing career, if the horse had had a start between 1 and 14 days prior to the case or control start, the type of jump race (hurdle or steeple), the calendar year of the start and the location of the racecourse were associated with fatality. CONCLUSIONS: The findings highlight the need to investigate further the differences between hurdle and steeplechase events and the adverse effect of prolonged prior flat racing careers on the risk of fatality in jump starts. POTENTIAL RELEVANCE: This is the first study to examine risk factors for fatality in jump starts in Victoria. The results should shape the development of interventions to reduce the risk in jump starts in the future.     

Fractures of the lateral malleolus of the tibia in 16 horses.

Clinical and radiological features of 16 horses with fractures of the lateral malleolus of the tibia are reported. The paper describes surgical techniques used, results obtained and discusses justification for removal. Fourteen fractures were unilateral and two bilateral. There was no left:right disparity. The history included a known traumatic incident in 14 cases. All animals had a tarsocrural joint effusion and 10 had palpable thickening of the lateral collateral ligaments. Crepitus was also palpable in 10 horses. The fracture was identified in all dorsoplantar and 14 of 18 dorsomedial-plantarolateral oblique radiographic projections. Nine fractures were simple and 9 comminuted. All fractures were removed via a tarsocrural arthrotomy. Approaches were dorsolateral in 14 joints, plantarolateral in 3 and dorsolateral and plantarolateral in 1. After an ascending exercise programme horses returned to work 6 months after surgery: 15 horses were free of lameness after 17-62 months, with 13 animals performing at a level similar to pre-injury standard.     

Risk factors for Thoroughbred racehorse fatality in flat starts in Victoria, Australia (1989-2004)

REASONS FOR PERFORMING STUDY: Research into risk factors specific for fatality in flat racing should be focused at a regional level as the risk factors may differ among countries and even regions within countries. OBJECTIVE: To identify risk factors for fatality of Thoroughbred racehorses in flat starts on all racecourses in Victoria, Australia between 1989 and 2004. METHODS: Fatalities comprised all horses that died during or immediately after a flat race or official flat trial, and all horses that were subjected to euthanasia within 24 h of an event in which an injury was sustained. The retrospective study involved 283 case starts and 3307 control starts. Univariable and multivariable backward stepwise logistic regression was used to identify risk factors for fatality at any one start. RESULTS: In the final multivariable model, horse gender, prior racing history, race length, racing year, racecourse location and track rating were associated with fatality. CONCLUSIONS: This study identified specific risk factors for fatality. The findings are consistent with the hypothesis that horses accumulating high speed exercise are predisposed to catastrophic injury. The study has also highlighted the need to investigate further the adverse effects of different track ratings on the incidence of injury and subsequent fatality. RELEVANCE: The results will facilitate the development of effective strategies to improve overall safety of horses and jockeys in flat racing in Victoria, Australia.     

Fractures of the carpus in racing thoroughbreds of the Japan Racing Association: Prevalence, location, and current modes of surgical therapy

From 1985 through 1994 approximately 39,800 Thoroughbred horses competed in over 3,400 races each year conducted by the Japan Racing Association (JRA). During this time the prevalence of fractures incurred during racing was 1.99, and 0.09% during training. Of these, 0.32% of the horses during racing died or were humanely destroyed as a direct result of their injuries. During 1994, 1,837 fractures occurred. The cuboidal bones of the carpus and the distal end of the radius accounted for 33.5% of all recorded fractures, with 47.4% of these occurring during racing and 24.2% occurring during training. The most common sites of fracture within the carpus were the distal end of the radius, the third carpal bone, and the radial carpal bone accounting for 35.3, 35.2, and 29.5% of fractures, respectively. Of these, 86/7% of osteochondral fractures occurred on the dorsal aspect of the cuboidal bones. At racing speed, characteristic fractures of the carpus are relatively common in race horses.Since 1991 in Japan, arthroscopic surgery has been the treatment of choice for the removal of carpal joint osteochondral fragments. Of all horses having arthroscopic surgery (n=155), 68.4% of these horses returned to race 9 months after surgery. Of all horses having osteochondral fractures of the distal end of the radius, radial carpal, and third carpal bones treated with arthroscopic surgery in 1993 (n=97) 52.6%, 60.0%, and 55.6% respectively, returned to race and competed at the same level of competition or higher compared with pre-operative racing performance. Arthroscopic surgery, as adapted by the JRA, is a useful technique for the treatment of carpal bone fractures in race horses; however, following surgery some horses had chronic arthritic changes associated with the surgical site. This suggests that the surgical methods and post-operative training program have to be re-evaluated.The objectives of this paper are to describe the prevalence, location, post-operative complication and racing performance for horses having cuboidal carpal bone fractures in racing Throughbreds of JRA.     

A survey of neurological diseases in horses

SUMMARY: Case records of 450 horses with signs of neurological disease are reviewed. One hundred and nineteen horses with neurological disease due to trauma were examined, of which 60 were due to spinal cord trauma, 47 to brain or cranial nerve trauma and 12 to peripheral nerve trauma. Cervical vertebral fractures/trauma were the most common injury. Basisphenold/basloccipital bone fractures were the most common form of cranial trauma and facial nerve paralysis the most common cranial nerve injury. Eighty-nine horses with neurological disease due to malformation were examined. Cervical vertebral malformation occurred in 83 horses and congenital defects in 6 foals. Neurological disease due to inflammation or infection occurred in 30 horses. The most common disease of this type was meningitis, which occurred in 11 horses and foals. Neoplasms in the CNS caused neurological disease in 8 horses. The final category was miscellaneous neurological disease, which was diagnosed in 204 horses. Diseases in this category included neonatal (28 cases), toxic/metabolic (27 cases), idiopathic (133 cases), degenerative (3 cases) and other neurological diseases (13 cases). The most common condition was idiopathic laryngeal hemiplegia (116 cases).
Where possible, diagnosis relied on a thorough neurological examination with use of ancillary tests in selected cases including rhinolaryngoscopy, radiography, myelography, ophthalmoscopy and cerebrospinal fluid analysis when indicated. In many cases necropsy and histopathological confirmation or diagnosis was necessary.     

Cervical vertebral fracture in a Thoroughbred filly with minimal neurological dysfunction

Vertebral fractures in horses are relatively common and often occur due to trauma. Clinical signs may range from neck pain and mild neurological dysfunction to tetraplegia and death. Severity of signs and prognosis depends on extent of damage to the spinal cord. In this Case Report, serial radiographs, which track the bony changes associated with fracture healing, were performed over one year. Although surgical techniques have been described to repair fractures to the vertebrae, patients with minimal neurological deficit may have a favourable outcome with conservative medical management, as in this case.